In conventional trailer floor assemblies, cross-members arranged transverse to the longitudinal axis of the trailer at spaced intervals along the length of the trailer support a plurality of overlaid plates or sheets typically fabricated of steel or aluminum. The cross-members, usually embodied as structural steel I-beams, are exposed on the underside of the trailer so as to create an undulating exterior surface with troughs between the cross-members. This increases wind drag and acts to collect dirt, ice and snow, road salt, asphalt and other materials, some of which are corrosive. The collected matter increases weight, further increases wind drag, and is a danger to trailing drivers when it dislodges.
To address this problem, U.S. Pat. No. 7,152,909 discloses a trailer floor constructed of a series of extruded aluminum panels arranged to extend transversely between left and right rails running along the length of the trailer. The rails are also extruded aluminum, and each rail defines a U-shaped channel that is open toward the center of the trailer for receiving left or right ends of the floor panels, as the case may be. As may be seen at FIGS. 6, and 7 of the '909 patent, the floor panels have top and bottom walls connected by a pair opposing side walls and by at least one vertical I-beam member located between the side walls. The floor panels include a rib projecting outward from one side wall and a groove along the out surface of the opposite side wall, whereby adjacent floor panels may be mated with one another as shown in FIG. 6A. Each corner of the floor panel extrusion includes a step or half-groove that cooperates with the step or half-groove on an adjacent floor panel to form a grove to receive welding material or an adhesive.
In the solution offered by the '909 patent, the floor panels are supported by a bottom horizontal leg portion of the U-shaped channel, which is a relatively thin aluminum wall projecting from the rest of the rail extrusion. This support arrangement may be too weak and not suitable in areas of high stress (e.g., king pin, landing dollies, and rear door), or in situations where the cargo load carried by the trailer is heavy and/or concentrated away from supported regions of the trailer floor.
What is needed is an improved trailer floor assembly that is stronger, particularly in areas of high stress (e.g., king pin, landing dollies, and rear door), and does not require welding or application of adhesive to join adjacent panels together during assembly. The trailer floor assembly should exhibit better aerodynamics and have a long useful life even when used on snowy and salt-covered roadways.